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Section 2-2 Problem Solving Using Estimation Strategies Page 54 in your book

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Section 2-2 Why do you estimate an answer before you calculate a problem?

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Why? So you know your answer is reasonable or not!!

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Example I want to buy a grilled cheese sandwich ( 1.89) and a frozen yogurt (1.49). What is the estimated amount? _________ I have $3.00, do I have enough? ________

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Different ways to round 1. Round to the nearest ½ dollar. 2. Fount-end estimation.

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Round to ½ dollar Example: Add 10.13 and 1.46 10.13 becomes _______ 1.46 becomes ________ ADD: _________

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Example 1. Example: Add 10.13 and 1.46 10.13 becomes 10.00 1.46 becomes 1.50 ADD: 11.50

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Example 2: you do this example in your head. Add $9.82 and $1.76 Answer: _______

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Example 2 Add $9.82 and $1.76 Answer: $12.00

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Rounding using front-end estimation Step 1: Look at the front numbers (the whole numbers) and add them. Step 2: Look at the end numbers (decimal numbers) and estimate the total amount to the whole number. Step 3: Write the Answer

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Example 1 Estimate the cost of a slice of pizza (1.45) and yogurt (1.39) Step 1: Add the front numbers they are ________= _____ Step 2: Add the estimate the end #’ers to the nearest whole number ________ Step 3: Answer ___________

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Example 2 Do this one in your head 3.20 and 1.87 Front _____ End _____ Answer _____

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Example 2 Do this one in your head 3.20 and 1.87 Front 3+1+4 End Approx 1 Answer so 4+1+ 5

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Estimation technique called clustering Estimate the sum: 2.8 +2.6 +2.2 + 2.5 + 2.4 = ____ Estimate each to the same decimal # in this case 2.5 So 2.5 x 5 = 12.5

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Another example of clustering Estimate 6.3 + 5.9 + 6.09 + 6.33 + 5.68 + 6.1 What number could these all be?? So ___ x ____ = _____

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Vocabulary word Compatible numbers: When you estimate quotients using numbers that are east to divide mentally. Example: 50.25 divided by 7.95 Estimate 50.25 becomes _______ 7.95 becomes ________ Estimated answer ______

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Review Today you learned: Why you use estimation strategies You learned to estimate by ½ dollar, front- end, and by clustering. You learned the vocabulary word: compatible numbers.

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Assignment Worksheet

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